Green Screen and Keylight difficulties, darker parts of subject

I have a series of clips I've green screened that I'm having trouble with. I'm using AE CS5 with Keylight 1.2, and there are a few spots in my subject that are really hard to deal with.

The upper portion of the body of my subject keys pretty good, no problems there. The legs are darker on the person, and once I adjust the threshold for the screen gain and clip black (in the status view) to remove the background, and check the subject, everything looks good except the legs have some chunks that are transparent. And they wiggle somewhat when playing back the clip.

Can anyone recommend a few tips for me to try out? I have limited time and thought I might be able to poke the brains of some pros here who might catch this post and have a helpful thing or two to share. I would appreciate it greatly, thanks!

Your Upload is ok.
That should be pretty easy
I'm testing your nice Psd with Keylight and is perfect (on a still image)
In AF you have several more options under the Keying panel to ad & play aroun....
If you still have problem i will recomend you to give a try to:http://www.redgiantsoftware.com/products/all/key-correct/

But I hope you could get more unswers from the Formu Gurus.
Let as (s)now where that mistical piano player will perform....Hope everything works fine.
Regards.
Nic

Thanks Niccolo. I think the problem I'm having is, there is wiggling and black spots in the boots of the player after I key, and start to use the clip in other things. I have a space background that is rolling by, and I can see the dark spots in the boots wiggle and change. I will try to do a test video and zoom in on the boots to show the problem.

Your sample is a very good one.
I agree with niccolo ungaro .
Key correct and composite wizard is a "must have".
For this shot i feel that primate will deliver better results.
i dont think you need to smooth any grain with Neat or else plugin.
Do a raw garbage matte using color range and matte chocker [ let green surrounding ]
and in step two use a fine keyer such as keylight or primate [ if you can afford them ]
In many cases black areas that we want them IN.
can be treated with lumma extraction as a separated layer .
hope it Helps.
* THE trick is in combining layers and keyers.

Thanks for the detailed reply Mr Agriosi! I am trying to wrap my head around the logistics of it, I'm only a month or so in to keying and editing and working with After Effects, some things with layers and comps confuse me. I will try to take things step by step but, I can't expect you to hold my hand and tell me every thing I need to do one at a time.

I will try to figure out how to use color range and matte choker, I've never done that before. I see you say the trick is in combining keyers and layers, but that is a little abstract at the moment. I will keep at it this evening, I appreciate your help!

I apologize if this is too elementary, but while you're doing your key in Keylight, switch the "Viewing" mode to "Combined Matte". You want all of the image that should be visible to be pure white, and all the rest to be pure black in this mode. If you monkey with your clip black and clip white (under Screen Matte), you should be able to get a pretty solid key off the image that you posted. If you're noticing graininess/artifacting after playing back the motion image, consider changing your "Replace Method" to "hard colour" instead of "soft colour". Hope this helps!